A conventional pet grooming device is a slicker brush, which comprises a grooming head attached to a handle. The head is usually in the form of a curved, generally rectangular bristle pad carrying an array of relatively fine metallic or polymeric bristles. A problem associated with slicker brushes is that hair removed from the pet by the slicker brush can become rapidly entangled between the bristles of the bristle pad. Consequently, a user may need to manually pull a mass of collected hair, together with any dander or other matter within the hair mass, from the bristle pad a number of times during grooming. Not only can this be an inconvenience for the user, but it can be unpleasant, particularly if the bristles are sharp or if the user is allergic to the matter removed from the pet.
In order to address this problem, it is known to provide brushes with retractable bristles. For example, U.S. Pat. No. 6,681,775 describes a brush having a handle and a bristle-receiving chamber connected to the handle. This chamber comprises a combing wall comprising a plurality of bristle-extension apertures, and a bristle pad comprising a plurality of bristles. The bristle pad is urged against the inner surface of the combing wall by a spring so that the bristles extend through the apertures. The bristle pad is connected to a lever which is rotatable about a pivot point against the biasing force of the spring to move the bristle pad away from the combing wall, thereby causing the bristles to retract within the chamber. This rotation may be effected by the thumb of the hand holding the brush, or by the other hand of the user. Hair or other matter entangled between the bristles will either fall from the brush as the bristles retract within the chamber or remain on the combing wall to be manually removed by the user. Once the combing wall has been cleaned the user releases the lever, resulting in the bristles being forced back through the apertures in the combing wall under the force of the spring.